The present invention relates in general to fuel-water separation arrangements which are used in conjunction with a fuel filter to separate water from fuel so that the accumulated water can be removed from the fuel filter. Removal of the water is typically accomplished by means of a valve-controlled drain. More specifically, the present invention relates to the design, packaging, and assembly of a water-in-fuel conditioning transducer, or as referred to herein, an integrated control module. The integrated control module of the present invention incorporates a solenoid-controlled drain valve with a water-in-fuel sensor and controller circuitry for detecting and removing water trapped in the collection bowl of a water-separating fuel filter.
The water which is separated from the diesel fuel and collected in the fuel filter bowl requires periodic draining in order to prevent loss of filter capacity and costly fuel system damage due to water ingestion. The integrated control module of the present invention detects the presence of this water and drains it from the fuel filter bowl. Water is detected by monitoring the impedance between two electrodes located inside the fuel filter water collection bowl. When the water detection criteria is met, the system automatically opens a solenoid-actuated drain valve for a predetermined length of time.
There are a number of earlier patent references which discuss the water-in-fuel concerns generally and which specifically evaluate the state-of-the-art in the field of diesel engine technology. While the focus of these earlier patent references is normally on a particular improvement or enhancement to the state of the art, it is still helpful to look at the background discussions in these references in order to understand the issues driving the particular inventive effort. For example, as explained in U.S. Pat. No. 5,534,161 which issued Jul. 9, 1996 to Tarr, et al., the use of water separators in diesel engine fuel filters is a well-known expedient to rid the fuel of contaminants that might cause a malfunction of the engine. Many of these earlier water separators consist merely of a water drainage reservoir at the bottom of the fuel filter connected by a drain tube which expels the water to the ground. Concern over such cavalier discharge of contaminated fluids into the environment has led to the design of water separators that collect the separated water in a container located at the bottom of the filter assembly. Such containment of the separated water requires that the driver of the vehicle periodically empty the separated water from the container prior to the container becoming full. A problem arises, however, in that the driver cannot always be relied upon to remember to empty the separated water when required. To overcome this problem, some water separators contain sensors which are activated when the water reaches a predetermined level in the reservoir, thereby energizing a signal light located on the dashboard of the vehicle which warns the driver of the need to drain the filter. However, such signals still require that the driver stop the vehicle and manually empty the separated water from the filter unit. This represents an inconvenience to the driver, and there is still no guarantee that the driver will not simply ignore the warning light on the dashboard. Accordingly, it was concluded that there was a need for a fuel system that provides for the automatic draining of water separated from the fuel in the fuel filter when such separated water reaches a predetermined level.
The invention which was conceived in the Tarr, et al. patent involves the design of an automatic water drain and priming pump for a fuel system in which a reversible pump is operable in a first direction to pump separated water out of a fuel filter and into a water drain and further operable in a second (opposite) direction to pump fuel into the fuel filter in order to prime the fuel pump. Operation of the pump in the first direction to drain water from the fuel filter is initiated by water-in-fuel sensors within the fuel filter. Operation of the pump in the second direction to prime the fuel pump is initiated by manual activation of a switch during servicing of the fuel filter.
While the invention of the '161 patent is believed to have achieved its objectives, there remain opportunities for further improvements. For example, the complexity of certain water-in-fuel drain systems is a disadvantage. Another disadvantage of earlier systems is the need to assemble numerous components and make various connections, one-by-one, in order to establish all of the system requirements.
It would be an improvement to existing fuel water separation units and the design of the water drain function to configure the water-in-fuel sensor and drain valve functions into an integrated control module which is designed to assemble directly to the wall of the fuel filter housing. In this manner, there is a design simplicity and efficiency. It is easy to fabricate the integrated control module of the present invention separate from the fuel filter, a feature which facilitates the repair of the fuel filter as well as the repair or replacement of the integrated control module. If operational problems occur with the integrated control module, for example, it can be readily disassembled, a replacement integrated control module attached, and the removed integrated control module evaluated for repair or replacement. When all of the components and connections are assembled together as loose, separate items, there is no integration and thus no integrated control module. Accordingly, there is no way to easily substitute a replacement integrated control module while the original equipment integrated control module is being evaluated and/or repaired.
The present invention provides an improvement to the current state of the art in the field of fuel water separation units by configuring an integrated control module which provides design simplicity and ease of assembly and use, all in a single package with a single external connection for the source of power. The package is designed for attachment directly to a fuel filter housing, either on the side (first embodiment) or onto the base (second embodiment).